1. Field of the Invention
The present invention relates to an imager having an auto focus function.
2. Description of the Related Art
An imager, for example a digital camera, may comprise an auto focus function. The auto focus function virtually provides a distance measuring area on an imaging area of an imaging sensor, and automatically brings a subject into focus by using a subject image that is incident on the imaging area. Japanese Unexamined Patent Publication (KOKAI) No. 2006-343509 discloses that in the case that such camera has a shake reduction system, the shake reduction system performs so as to move the distance measuring area on the imaging area based on the amount of shaking a camera undergoes while the auto focus function is in effect.
However, if a subject image is not incident on an imaging area, the effect that an imager experiences from shaking is not reduced during auto-focusing. This may make it impossible for a camera to automatically maintain a subject image in focus on an imaging sensor.